Here it is
[attachment id=0 msg=3231]

QuoteWhen 20 mg of ionic solid XY (number of formula unit per unit cell is four) is added in 100 mL solution, it
forms a saturated solution. If density of XY Crystal is 1/6 g/cm^3, then radius of cation and anioo (in nm) is
(Use ideal radius ratio r_cation/r anion = 0.414 , Take NA = 6 * 10^23, Ksp =10^-10

Answer of question 30
Using the Ksp  value and the mg of ionic solid which is needed to make the saturated solution we can calculate the molar mass of the ionic compound.
From Ksp  you can calculate the molar solubility of XY  compound which means you know how many moles of XY are present in1000 mL water and it can be  easily converted into 100 ml of water.
If molar solubility of compound is s then it means
  s^2 = Ksp
so s = 1.0*10^-5 mol/L
It means 10^-4 moles in 100 ml
Now you know 20mg 10^-3 moles.
Convert this to molar mass.
The crystal is FCC
density = Z*N/V*N_A
V = a³= Z*N/d*N_A
But a/2= r₊ + r_-
Now use simple math to calculate r_-=0.707nm
 

Q31
The equivalent weight of XY is 85.5 and the molar mass calculated in question 30 is 200 .Hence the n factor is
200/80.5 means 2.33 .Now we  know the normality  of the solution is  2.565 / 85.5 * 1 and the molarity of the solution is 2.33 times normality of the solution.
Osmotic pressure =i MRT
Plug in values and calculate i
Once you know Van't Hoff factor and degree of dissociation is 1, it means the compound is fully dissociated so you can easily pick up the right formula of the compound also

Answer question 32
Lithium fluoride has very small lithium ion  and fluoride ion so very high lattice enthalpy and high covalent character due to this the solubility of lithium fluoride as compared to potassium ferrocyanide is very low.
Lithium fluoride solubility is very less or is nearly insoluble in water means it has less conductivity in water as compare to compound 1
Zinc blend has fcc packing in which Zn²⁺ has a coordination number of 4.
Zinc compounds are white because it has fully filled 3d subshells  in its 2 + oxidation State